Wind Turbine Zone

Friday, March 13, 2009

In the last decade, we have heard more and more about the need of renewable clean energy, but not much has been done. Today, pollution and greenhouse gases are at its peak all over the world and the price of oil is higher than ever. Our earth is getting very sick, and it is time that we start contributing in fighting pollution by exploiting renewable clean energy. These clean energy consist of solar energy, wind power, geothermal heat, hydroelectricity, biofuels, and more. Currently, the wind power energy is the most popular of all of these green technologies. Thousands of wind turbines are being invested and installed everywhere worldwide. Thus, many questions arise. What is a wind turbine? What are the different types of design? What are the advantages and disadvantages? How do the aerodynamic blades work? Are these wind turbines worth investing? Is it feasible? Will they help us significantly in reducing greenhouse gases? And what are impacts of wind turbine in our environment? These are the questions that I will attempt to answer.

The definition of a wind turbine is a machine that converts the wind’s kinetic energy into rotary mechanical energy and this rotary mechanical energy is then converted by the generator into electricity.

Wind turbine usually has six main components: the rotor, the gearbox, the generator, the control and protection system, the tower and the foundation. These main components can be seen in the figure below.

Rotor

The rotor takes the wind and aerodynamically converts its energy into mechanical energy through a connected shaft.

Gearbox

The gearbox increases the rotational velocity of the shaft for the generator. In some turbines, the gearbox is not needed because the rotational velocity or the torque from the shaft high enough.

Generator

The generator is a device that produces electricity when mechanical work is given to the system.

Control and Protection System

The protection system is like a safety feature that makes sure that the turbine will not be working under dangerous condition.

Tower

The tower is the main shaft that connects rotor to the foundation. It also raises the rotor high in the air where we can find stronger winds.

Foundation

The foundation or the base supports the entire wind turbine and make sure that it is well fixed onto the ground.

There are mainly two types of wind turbine: horizontal axis and vertical axis. The horizontal axis wind turbine (HAWT) and the vertical axis wind turbine (VAWT) are classified or differentiated by the axis of rotation the rotor shafts.

The wind turbine shown in figure below is a horizontal axis wind turbine. It is the most popular wind turbine used and it can be seen all around the world because of its higher efficiency than vertical axis turbines. The HAWT usually have their generator place on the top and they have a propeller-type rotor.

The vertical axis wind turbine however isn’t as popular as HAWT, but because the axis of rotation is vertical, it allows a better originality or creativity in the design of the configuration of the blades. There are many VAWT sub-types: Darrius (shown in figure below), Neo-aerodynamic, Novel, Savonius, Zephyr, etc. These sub-types all have different blade configuration. The VAWT have their gearbox near the ground.

An advantage that most HAWT have is a wind vane attached on the rotor blades which would orient the blades towards the wind, allowing thus the best angle of attack for the blades. In doing so, this would give the wind turbine the maximum amount of wind energy possible. Another advantage is the towers of HAWT are relatively taller than VAWT, which allows the blades to face much higher velocity winds in high altitude. In some places, the power output of the wind turbine could increase up to 34% every ten meters in altitude because the wind speed is increased by 20%. Taller towers wind turbine can also be placed on uneven land or in offshore sites. Some financial benefits of HAWT is that it becomes cheaper at high production volumes and larger sizes. They are also more efficient and have higher capacity factors than VAWT.